Flow reactor synthesis of polymers

ABSTRACT

A flow reactor system and methods having tubing useful as polymerization chamber. The flow reactor has at least one inlet and at least one mixing chamber, and an outlet. The method includes providing two phases, an aqueous phase and a non-aqueous phase and forming an emulsion for introduction into the flow reactor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/882,073, filed Oct. 13, 2015, now U.S. Pat. No.9,481,764, entitled “FLOW REACTOR SYNTHESIS OF POLYMERS”, the contentsof which are incorporated herein by reference.

By appropriate design of the chemical structure, conjugated polymericmaterials can be used as additives providing anti-corrosive andanti-static properties or employed in electronic applications such asorganic light-emitting diodes (OLED), solar cells, semiconductors,display screens and chemical sensors. Conjugated polymeric materials,however, typically suffer from high manufacturing costs, materialinconsistencies and processing difficulties when prepared by batchprocesses.

Despite these advances, using current methods there are limitations tothe expanded use of conductive polymers. For example, polyaniline (PANIor “emeraldine”) is one such conductive polymer that, due to highmanufacturing costs, material inconsistencies and batch processingdifficulties, is not fully exploited. PANI is widely used in printedboard manufacturing as a final finish; protecting the copper andsoldered circuits from corrosion. PANI is commonly prepared by chemicaloxidative polymerization of aniline in an aqueous solution. Materialobtained by this approach is amorphous and insoluble in most organicsolvents. PANI reaction times are relatively long (e.g., many hours).Many of the current flow reactors under evaluation use microfluidicchips or miniaturized columns and specialized equipment for control ofthe flow devices that adds cost and complexity to the process.

SUMMARY

In a first embodiment, method is provided, the method comprising formingan emulsion of a monomer and an acid; introducing the emulsion into aflow reactor, the flow reactor comprising a length of tubing of innerdiameter between about 1 to about 4000 microns; and polymerizing themonomer and forming the acid salt thereof.

In one aspect, the method further comprises recovering the salt of thepolymerized monomer. In another aspect, alone or in combination with anyof the previous aspects, the method further comprises introducing acatalyst to the emulsion or the flow reactor.

In another aspect, alone or in combination with any of the previousaspects, the emulsion comprises an aqueous solution of the monomer andan organic solvent solution of the acid.

In another aspect, alone or in combination with any of the previousaspects, the length of tubing is coiled.

In another aspect, alone or in combination with any of the previousaspects, the salt of the polymerized monomer is substantially containedin the length of tubing, wherein the tubing is a fluoropolymer. Inanother aspect, alone or in combination with any of the previousaspects, further comprising removing unreacted material from the tubingwith water. In another aspect, alone or in combination with any of theprevious aspects, the method further comprises recovering the salt ofthe polymerized monomer from the tubing with organic solvent.

In a second embodiment, a method is provided, the method comprisingforming an emulsion of aniline and an organic or sulfonic acid;introducing the emulsion into a flow reactor, the flow reactorcomprising a length of tubing of inner diameter between about 1 to about4000 microns; and introducing an oxidant to the emulsion or the flowreactor; and polymerizing the aniline in the inner diameter of thelength of tubing and forming the acid salt thereof.

In one aspect, the length of tubing is coiled. In another aspect, aloneor in combination with any of the previous aspects, the salt of thepolymerized aniline is substantially contained in the length of tubing,wherein the tubing is a fluoropolymer.

In another aspect, alone or in combination with any of the previousaspects, the method further comprises recovering the salt of thepolymerized aniline from the tubing with organic solvent.

In another aspect, alone or in combination with any of the previousaspects, the molar ratio of the aniline to the organic or sulfonic acidis between 1 and 0.2. In another aspect, alone or in combination withany of the previous aspects, the total flow rate for the aniline isabout 0.01 mmole/min to about 0.2 mmole/min, resulting in an emulsionreaction mixture flow rate of 0.1 mL/min to about 0.5 mL/min into theflow reactor. In another aspect, alone or in combination with any of theprevious aspects, the oxidant is introduced at a flow rate from about0.001 to about 0.2 mL/min.

In a third embodiment, polymerization apparatus is provided for reactingone or more monomers producing one or more polymers, the polymerizationapparatus comprising: an amount of tubing of inner diameter betweenabout 1 to about 1000 microns, the tubing including at least one inletand at least one outlet, the amount of tubing having at least one inletport for receiving a reactant composition and at least one outlet port;a temperature controller sized to receive at least a portion of thetubing; a mixing chamber, the mixing chamber having an outletfluidically coupled to the inlet of the tubing, and an inlet; and atleast one fluid flow control device fluidically coupled to the inlet ofthe mixing chamber.

In one aspect, the tubing is wound around the temperature controller.

In another aspect, alone or in combination with any of the previousaspects, the at least one fluid control device comprises a monomer fluidflow control device and an acid fluid flow control device. In anotheraspect, alone or in combination with any of the previous aspects, theapparatus further comprises a second mixing chamber fluidically coupledto the outlet of the mixing chamber and the inlet of the tubing. Inanother aspect, alone or in combination with any of the previousaspects, the apparatus further comprises a catalyst fluid flow controldevice fluidically coupled to the second mixing chamber or to thetubing.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the present disclosure are apparent by referenceto the detailed description when considered in conjunction with thefigures, which are not to scale, wherein like reference numbers indicatelike elements throughout the several views.

FIG. 1A is a diagram of an exemplary flow reactor system as disclosedand described herein.

FIG. 1B is a diagram of an exemplary series flow reactor system asdisclosed and described herein.

FIG. 1C is a diagram of an exemplary parallel flow reactor system asdisclosed and described herein.

FIG. 2 is a diagram of another exemplary flow reactor system asdisclosed herein.

FIG. 3 is a diagram of another exemplary flow reactor system asdisclosed and described herein.

FIG. 4 is a diagram of a spool flow reactor as disclosed and describedherein.

FIG. 5 is a process flow diagram of a polymerization method using thesystem and methods disclosed and described herein.

FIG. 6 is a cross-sectional view of the flow reactor inner diameterarea.

FIG. 7 is a cross-sectional view of the flow reactor inner diameter areawith conductive polymer reaction product occupying a portion of theinner diameter area.

FIG. 8 is a graphical representation of exemplary back pressure versusreaction time in accordance with the present disclosure.

FIG. 9 is a process flow diagram of a polymerization method using thesystem and methods disclosed and described herein.

FIG. 10 is a process flow diagram of a polymerization method ofPANI-DNNSA using the system and methods disclosed and described herein.

FIG. 11 is a UV-Vis spectrum of PANI-DNNSA prepared using the system andmethods disclosed and described herein.

DETAILED DESCRIPTION

A preparation of polyaniline-dinonylnaphthalene sulfonic acid (DNNSA)(hereinafter also referred to as “PANI-DNNSA”) as a solvent-solublepolymer by flow reactor chemical processing is disclosed herein. Thedisclosed system and methods provide unique processing sequences fordirect collection of the purified emeraldine salt without post reactormanipulation. The present systems and methods provide improvement overknown methods of synthesizing conductive polymers, and in particularconductive polymer salts, for example, PANI-DNNSA using very shortreaction times not otherwise obtainable using conventional methods,which require long reaction times.

By way of example, the present systems and methods provides improvementin the efficient and controlled synthesis of polyaniline (PANI) salt asa soluble, intrinsically conductive polymer. A continuous flow synthesisof PANI dinonylnaphthalene sulfonic acid salt (PANI-DNNSA) or“emeraldine salt” is herein described using a flow reactor. In someexamples the flow reactor comprises a microfluidic (1 to about 750 umI.D.) tube reactor. In some examples, the microfluidic tube comprises afluoropolymer, e.g., TEFLON®. The tube reactor provides a suitablesurface for deposition of the forming polymer and a straightforwardpurification of the conductive polymer salt.

As used herein, the phrase “flow reactor” is inclusive of a micro-flowreactor. A micro-flow reactor is used herein as a flow reactor havingflow dimensions, e.g., tubing inner diameter (I. D.), less than 1 mm(1000 microns).

As further described below, in some examples as the polymerizationreaction preceded, the majority of the polymer product deposits on thewalls of the tubing. The polymeric product can be purified by washingwith water to remove aqueous soluble reactants, reagents, and sideproducts.

The conductive polymer salts formed in the flow reactor and deposited onthe walls of the tubing can be eluted with organic solvent to providesoluble conductive polymer salt suitable for solid casting, filmforming, or precipitation. The method provides for the preparation ofconductive polymer salts having a ratio of conductive polymer monomer tosalt of about 1:1 to about 1:0.2. The apparatus is configurable forin-situ characterization e.g., by UV-Vis spectroscopy, infrared, and/ormass spectroscopy.

An apparatus and related methods for polymerizing at least one reactantare described. In certain examples, the apparatus is a microfluidicapparatus comprising a mixing chamber and microchannel. In addition, thereactor can further comprise an output chamber and a detection unit thatis operatively connected to the microchannel.

With reference to FIG. 1A, flow reactor system 100 shown. First reactant10 and second reactant 20 are introduced to first mixing unit 30. Thereactor system 100 shown in FIG. 1A can produce conductive polymer salts(mass/per unit time) more efficiently than conventional macroscaledevices or batch reactors. Flow reactor 100 is capable of operating at arange of processing temperatures from room temperature to about 250° C.,and most advantageously at process temperatures less than 100° C. Roomtemperature is inclusive of at least above the freezing point of waterto less than the boiling point of water. In some examples, ambienttemperature is between about 50° F. (10° C.) to about 90° F. (32° C.).In some examples reactants 10, 20 are introduced, independently, to thefirst mixing unit 30 at a predetermined flow rate and/or predeterminedconcentration such that a desired molar ratio of reactants 10, 20 aremixed prior to being introduced to the flow reactor. In other examples,reactants 10, 20 are introduced together to the first mixing unit 30such that a desired molar ratio of reactants 10, 20 are mixed prior tobeing introduced to the flow reactor. First mixing unit 30 can be anyconventional mixing device. In some examples, the mixing device is ahigh-speed or ultrahigh speed mixing device capable of emulsifying oneor more solutions, for example an aqueous solution and a non-aqueoussolution. In some examples, first reactant 10 is contained in an aqueoussolution and second reactant 20 is contained in a non-aqueous solution,whereas first mixing unit 30 is designed for emulsifying first reactant10 and second reactant 20. Third reactant 50 joins first and secondreactants in second mixing unit 60. In some examples, reactant 50 is acatalyst. After mixing and second mixing unit 60, reactants areintroduced to tubing 70 via inlet port 65. Tubing 70 comprises dischargeport 80, which can be monitored by analysis equipment 90. Analysisequipment 90 can include spectroscopic equipment to interrogate andanalyze materials flowing from discharge port 80, such as unreactedmaterials and/or reaction products. Spectroscopic equipment includesUV-Vis, IR (near-, mid-, and far-IR), and mass spectroscopy. Otheranalytical and interrogating techniques can be used, such ascapacitance, pH, etc. Pressure regulating unit 67 can be positioned atthe outlet of flow reactor 70 for monitoring a change in pressure duringpolymerization or during the collection step of polymerized material andinformation from pressure regulating unit 67 can be used by a controllerto cease introduction of the monomer to the flow reactor. An additionalpressure regulating unit 67 can also be positioned at the inlet of flowreactor 70 for example, for monitoring changes in pressure during theprocess. Fluid lines 69 can be independently fluidically coupled to flowreactor 70 so as to introduce purging media 66 (e.g., water) orcollecting medium 68 (e.g., solvent) for collecting polymerizationproduct from flow reactor units 70.

In some examples, flow reactor system 100 has a single inlet port to thetubing 70. In other examples, flow reactor system 100 has additionalinlet ports positioned between inlet port 65 and discharge port 80. Asshown in FIG. 1A, tubing 70 can be coiled around to provide an extendedtubular flow reactor.

In some examples, tubing 70 is contained in housing 40 that providestemperature control and/or support and/or protection from damage of thetubing 70. In some examples, housing 70 has an inside surfacesurrounding at least a portion of the tubing 70 such that the coiledtubing 70 is at least partially contained within the housing 40. In someexamples, housing 40 is configured to provide temperature control to thetubing 70, which includes heating and/or cooling.

As shown in FIG. 1B, alternate flow reactor configuration 100 a is shownwith plurality of tubing 70 a, 70 b arranged in a coil configurationcoupled in series. Tubing 70 a, 70 b can be dimensionally the same orcan have different lengths and/or different inner diameters. In thisconfiguration, the housing can be bifurcated into separate, sections 40a, 40 b receiving tubing 70 a, and 70 b that can be independentlymanipulated for heating and/or cooling the tubing. Alternatively, flowreactor configuration 100 a can have a single housing receiving tubing70 a, 70 b. In contrast to a parallel array configuration of the tubing,where the process stream is split prior to entering the flow reactor,the series array maximizes the amount of time that the reaction mixtureis maintained in a diffusion-limiting condition. While not to be held byany particular theory, it is believed that maintaining the reactionmixture in a diffusion limiting condition provides improvement of thepresently disclosed reactions for producing conductive polymer saltsfrom reactants in emulsion compared to batch processing. The presentmethods and systems disclosed herein provide for such a diffusionlimiting condition for the emulsion of reactants.

With reference to FIG. 1C, an exemplary flow reactor system 100 b isshown. A plurality of flow reactor units 70 c, 70 d, and 70 e, are shownin a parallel flow configuration. Each flow reactor 70 c, 70 d, and 70e, independently, can be isolated via flow control valves 63 situated atthe inlet and outlet of each flow reactor introduction of monomersolution to the corresponding flow reactor. Flow control valves 63 canbe manually operated and/or solenoid-based configured forcomputer-control using conventional controlling devices. Flow controlvalves 63 can contain one or more check valves for preventing backflowof dispersion solution. One or more pressure regulating units 67 can bepositioned at the outlet of one or more of the flow reactors formonitoring a change in pressure during polymerization or during thecollection step of polymerized material. Additional pressure regulatingunits 67 can also be positioned at the inlet of each flow reactor. Flowcontrol valves 63 can be coupled to pressure data from the controller soas to isolate one or more of the flow reactors 70 c, 70 d, and 70 e, foractivating purge and/or polymer recovery. In this configuration, flowreactor system 100 b can be continuously operated by selectivelyisolating one or more flow reactor units 70 c, 70 d, and 70 e forcollecting polymerization product and/or maintenance while maintainingmonomer introduction to one or more of the remaining flow reactor units.Alternatively, flow reactor system 100 b can be semi-continuouslyoperated, for example by temporarily ceasing the introduction of monomerto one or more of the flow reactor units 70 c, 70 d, and 70 e.Additional fluid lines 69 can be independently fluidically coupled toone or more of the flow control valves 63 so as to introduce purgingmedia 66 (e.g., water) or collecting medium 68 (e.g., solvent) forcollecting polymerization product selectively from one or more flowreactor units 70 c, 70 d, and 70 e. One or more of flow reactor units 70c, 70 d, and 70 e can be physically removed from flow reactor system 100b for transport with or without polymerization product recovered from inthe inner diameter of the tubing.

With reference now to FIGS. 2 and 3, alternate flow reactorconfigurations are shown. Thus, system 100 b has a linear tubing 70arrangement. In some examples, the cross-section of the tubing 70 in thesystem 100 b is rectangular or other shapes with cross-sectionaldimensions each independently of about 100 micron to 4000 microns. FIG.3 shows system 100 c that includes pumping equipment 15, 25, 55 forintroducing reactants 10, 20, and 52 mixing units 30, 60. Pumpingequipment can include syringe pumps, rotary valve pumps, displacementpumps and the like.

With reference to FIG. 4, in some examples, tubing 70 is coiled or woundas shown on or about the surface of temperature control member 75.Temperature control member 75 is of a length L separated by member 78,which can be a cylinder, between members 75 a, 75 b of height H forproviding the predetermined length of tubing and/or support and/orheating/cooling. In some examples, tubing 70 is coiled or woundsubstantially about the surface of temperature control member 75. Thelongitudinal axis of the surface of temperature control member 75 (asshown by line B-B) is substantially perpendicular to the turns of thetubing 70. In some examples, for a large temperature control membercomposed of a metal block with resistance heating, the system can beconfigured to allow heat to enter from the block (inner side of thecoiled or wound tubing) and at least partially exit through convectionthrough the outside against the environment. For configurations of theflow reactor system 100 that may require the reactor to be run withcooling, a complete immersion of the reactor tubing in housing 40 can beprovided. In other examples, tubing 70 is not wound coils but some otherarrangement configured for heat management from all sides of the tubing,not just one side or face. Temperature control member 75 can beconfigured for cooling medium or for receiving an electrical resistanceheating or other forms of heat that can be controlled by one or moreprocessors configured to a control unit. In one aspect, coiled tubing 70is essentially the same interior diameter throughout the coiled section.In other aspects the interior diameter of coiled tubing 70 varies frominlet port 65 to discharge port 80.

In some examples, housing 40 is used in combination with temperaturecontrol member 75. The housing can be constructed of metal, ceramic, orplastic and may include one or more of heating elements, coolingelements, temperature sensors, pressure sensors and the like. Tubing 70can be encompassed by housing 40 to provide support and/or protection.In some examples, the flow reactor system 100 is a microfluidic reactor.In one aspect, reactor system 100, comprises microfluidic tubing 70,such as tubing with an inner diameter of less than about 1000 microns,less than about 900 microns, or less than about 800 microns to a minimumdiameter of about 100 microns, coiled or wound into a coil about anouter surface of temperature control member 75. In some examples, theturns of the tubing 70 are very closely spaced with one another. In someexamples, the distance, independently, between one or more turns of thetubing 70 is between about zero (0) and 100 microns. In some examples,turns do not result in the touching of the tubing. In other examples,turns of the tubing result in restricting or preventing airflow betweenthe turns of the tubing for improving heat management.

In other examples, housing 40 is a climate controlled environmentconfigured for heating and/or cooling of the tubing. In such aconfiguration, spacing between turns of the tubing 70 can be used tofacilitate heat management. Heat management configurations of thehousing 40 in combination with the tubing 70 can comprise the use ofeither liquid, solid, or gas.

With reference to FIG. 5, process flow 101 is depicted as exemplary ofthe methods disclosed herein. Thus preparing an emulsion of aqueousmonomer and a salt in a non-aqueous solvent is depicted in Step 105.Introducing the emulsion and a catalyst to the micro reactor tubing isdepicted in Step 110. After predetermined time, flow of one or more ofthe reactants can be terminated and optionally, flushing of the microreactor tubing with water can be performed as shown in Step 115. Step115 can be performed so as to remove unreacted reactants and/or lowmolecular weight products. Recovering polymer from the micro reactortubing with organic solvent is performed in Step 120.

With regard to FIGS. 6 and 7, a sectional view of the tubing 70 withinternal surface 71 of tube bore having an internal diameter D. in someexamples, a maximum diameter is less than the diameter at whichadvantages of diffusion-limited reaction diminishes. This maximumdiameter can be as much as 4000 microns, similar to tubing diameter usedfor high pressure tubing. In other examples, optimal results may beobtained using diameters less than 4000 microns, less than 3000 microns,or less than 1000 microns to a minimum diameter of about 100 microns.While not to be held to any particular theory, it is believed thatfaster reaction rates for the reactions disclosed and described hereinoccur with decreasing reactor tubing inner diameter dimensions, as muchas 10⁴ to 10⁶ in microfluidic systems as previously reported with sometrade-off of reaction volume per unit time. In one example the capillaryto 70 is made of glass, metal, plastic or glass or metal that is coatedon its inner surface with a polymer e.g. a fluoropolymer. The tubing maybe encased in another polymer or be metal coated.

Tubing length can be chosen based on the ability of the selectedcomponents of the system (pump, tubing burst strength, fittings, etc.)to handle pressure. The maximum length of tubing suitable for use withthe presently disclosed system is a function of back-pressure and theability to transport product through the entire length of the tubing. Insome examples, the system can be configured to operate at a tubinglength coupled with a tubing inner diameter such that the systemoperates at or below about 20 bar (280 psi). In some examples, thelength of tubing does not exceed 500 meters with tubing having an innerdiameter of less than 4000 microns. In other examples, the tubing 70 istubing of diameter less than 1000 microns (microfluidic tubing) with alength of about 100 meters or less. Other combinations of tubingdiameter and to be length can be used commensurate with the operatingparameters of the system and the desired reaction volume per unit time.

The cross-section of the tubing may be any shape, but preferably iscircular. In some examples, polymerization occurs on internal surface 71of tube bore as shown in FIG. 7 where polymerization product 73restricts the internal diameter D to a reduced diameter D′. In someexamples, the tubing inner diameter or the reduction in internaldiameter D is symmetrical about longitudinal axes A-A, B-B. In someexamples, the tubing inner diameter or the reduction in internaldiameter D is non-symmetrical about longitudinal axes A-A, B-B. Thisreduction in diameter D to diameter D′ of the tubing 70 causes a backpressure that can be measured and/or used in part to control the processherein.

As shown in FIG. 8, this back pressure can be monitored whereas at thebeginning of polymerization back pressure 400 at time T1 is consistentwith the viscosity and flow rate of the emulsified reactant mixturebeing fed into tubing 70. During a time period T2, where polymerizationhas caused a reduction in the internal diameter of tubing 70, the backpressure begins to increase and approaches a threshold 450. In someexamples the system is designed to terminate polymerization when theback pressure value 420 reaches the predetermined threshold 450. Therate of change of the back pressure as depicted in time period T2 can beadjusted taking into account the burst strength of the capillary tubingand other reactor parameters by manipulation of the viscosity of thereactants, the molar concentration of the reactants and/or catalyst,temperature, flow rates and combinations thereof. FIG. 9 depicts aprocess flow diagram 200 that represents an example of the presentlydisclosed method. Thus, pumping reactant emulsion and catalyst into themicro reactor tubing is depicted by Step 205. Monitoring back pressureof the reactant emulsion during the polymerization process is depictedin Step 210. Using conventional pressure monitoring equipment eitherexternal or electrical with the pumping devices is envisioned.Introduction of the reactant emulsion is terminated once the thresholdback pressure is reached as depicted in Step 215. Recovering the productpolymer from the micro reactor tubing by flushing with organic solventis depicted in Step 220.

By way of example, the method disclosed herein can be applied to themanufacture of conjugated conductive polymerpolyaniline-dinonylnaphthalene sulfonic acid salt (“PANI-DNNSA”), whichis a conductive polymer for electronic applications such as organiclight-emitting diodes (OLED), solar cells, semiconductors, displayscreens and chemical sensors.

Thus, and an exemplary example, a continuous flow synthesis process ofPANI-DNNSA salt is provided. The flow apparatus was designed to allowaddition of the oxidative reagent to a preformed emulsion of aqueousaniline and the organic soluble DNNSA. Our first test case evaluates theemulsion polymerization of equimolar amounts of aniline and DNNSA in thepresence of ammonium persulfate as the oxidative catalyst. The reactionis depicted below in Equation (1):

Thus, with reference to FIG. 10, process flow diagram 300 is shown.Steps 302 and 304 introduce an aqueous composition comprising anilineand a non-aqueous composition comprising dinonylnaphthalene sulfonicacid (DNNSA), respectively into a first mixer. Forming a reactantemulsion in the first mixer is performed in Step 310. Introducing acatalyst and the reactant emulsion into a second mixer is performed inStep 315. Introducing to the micro reactor tubing and obtaining athreshold back pressure is performed in Step 320. Terminatingintroduction of reactant emulsion and catalyst to micro reactor tubingis performed in step 325. Optionally, the micro reactor tubing can beflushed with water in Step 330 to remove unreacted material and/or lowmolecular weight polymer. Recovering polyaniline polymer salt from microreactor tubing with organic solvent is carried out in Step 335.

Experimental Section

Dinonylnaphthalene sulfonic acid (DNNSA) was obtained from KingIndustries (Norwalk, Conn., USA) as a 50% w/w solution in n-butylglycol.The UV-Vis spectra were collected using a Hitachi U-3900 spectrometer. Afilm of the sample was prepared by drying a xylene solution in a quartzcuvette overnight and subsequent drying in vacuo. The cuvettes wereplaced on the side to allow for a consistent film to form over thequartz glass. Impurity profiles of the PANI:DNNSA samples were analyzedby reverse phase High Performance Liquid Chromatography (HPLC) to checkfor residual starting materials and solvents.

Flow Equipment. A tubular flow reactor coil was prepared from 1/16″O.D.×0.031″ I.D. TEFLON® tubing of approximately 21 m (70 ft) in Length.The tubing was wrapped around an aluminum spool 4″ in diameter with aheight of 4.25″. These dimensions for the spool allow for a single layerof 65 turns of the TEFLON® tubing. A calculated volume of the TEFLON®flow reactor was 10.4 mL based on the dimensions. Measured volumeincluding dead volume before and after the reactor coil was 11.4 mL. Theassembled TEFLON® flow reactor was fitted to a custom built aluminumspindle fitted with a 120V Firewire heater. Temperature control wasachieved with a Model 150 J-KEM temperature controller (J-KEMScientific, Inc., St. Louis, Mo.) attached to a K-type thermocouple andthe heating unit in the aluminum block. Reagents were introduced intothe reactor coil by the use of three separated syringe pumps equippedwith plastic or glass syringes. Two KD Scientific (K-100 and K-250) anda Sage (Model #355) syringe pumps were employed. The first mixer forcombining solutions of aniline and DNNSA consisted of a modified RaininHPLC mixer unit with a magnetically driven TEFLON® stirrer in astainless steel cylinder. Introduction of the oxidation catalystammonium persulfate was carried out with a standard HPLC T-fitting (SS,0.040″ I.D.). Collection of fractions from the reactor coil was achievedeither by manually changing fractions or with a Gilson 203B fractioncollector. Components of the flow system were connected with standard1/16″ TEFLON® tubing and HPLC grade fittings of either stainless steelor polyetheretherketone (PEEK).

Synthesis of Polyaniline-dinonylnaphthalene sulfonic acid (1 mmolscale). The flow system herein described as in FIG. 3, was equilibratedwith water from all three syringes at a total initial flow rate of 0.427mL/min to dislodge any air or bubbles in the flow reactor coil. Thetemperature of the coil was maintained at 25° C. throughout the process.Once the air was displaced from the system, the syringes in each of thepumps were exchanged with the appropriate reagent. Syringe pump A (Sagepump) was fitted with a 60 mL plastic syringe containing a freshlyprepared solution of 0.375M aniline in distilled, deionized water. TheKD Scientific pumps B and C were equipped with 20 mL of 1.0M DNNSA inn-butylglycol in a 20 mL plastic syringe and 10 mL of 2.0M ammoniumpersulfate in a 10 mL plastic syringe, respectively. Based on the abovevolumes of material introduced into the reactor coil, the reaction scalewas designated as a 1 mmole scale. Pumps A (aniline: 0.277 mL/min) and B(DNNSA: 0.1 mL/min) were initiated to start formation of theaniline-DNNSA emulsion. Once the white emulsion reached with secondT-mixer, pump C (oxidant: 0.05 mL/min) was started for initiation of thereaction. After a period of time the flow rate was observed to rapidlydecline due to increasing back pressure in the system. It was observedin this example that the first 10 mL that exited from the reactor coilcontained a heterogeneous mixture of the PANI polymer in the organicphase and some aqueous phase byproducts. This initial fraction wasextracted with xylene and the extract washed twice with water. The driedorganic layer of this solvent extract was concentrated in vacuo toafford 0.10 g of a blue-green film (UV-Vis spectra 500 in FIG. 11).UV-Vis (dried film) 285, 325, 373, 851 nm; Elemental Analysis: C, 72.64;H, 10.01; N, 1.84; S, 5.41. After a total of about 30 min, flow frompump A was stopped. In one example, the reagent syringes were replacedwith syringes containing water to terminate the polymerization in theflow reactor.

In this example, after polymerization was terminated, the flow reactorwas flushed with an amount of water to remove any water solublereactants or by-products. No PANI products were collected from thiswater flush and the significant blue color remained in the flow reactortubing. Following this water flush, the reactor was then flushed with anamount of xylene and the wash collected gave a concentrated blueextract. The solvent extract was dried and concentrated in vacuo toafford 0.31 g of a blue-green film. UV-Vis (dried film) 285, 325, 371,839 nm, is shown in FIG. 11 as spectra 550. Elemental Analysis: C,73.49; H, 10.42; N, 1.87; S, 5.14.

Synthesis of Polyaniline-dinonylnaphthalene sulfonic acid (7.5 mmolscale). The flow reactor system was setup as described for the previous1 mmole scale reaction, however the positions of the pumps and size ofthe syringes were changed to overcome the initial backpressure fromformation and deposition of polymeric material in the flow reactor.Using smaller syringes, the pumps were outfitted as follows: Pump A: 20mL syringe of 0.375M aniline, KD Scientific pump; Pump B: 10 mL syringeof 1 M DNNSA solution, KD Scientific pump. Pump C: 10 mL syringe of 2M(NH₄)₂S₂O₈, Sage pump. Samples were collected in 3.5 mL fractions. Theinitial heterogeneous fractions were worked up as described previouslyto yield 0.206 g of a blue-green residue. UV-Vis (dried film) 285, 325,802; Elemental Analysis: C, 72.70; H, 9.83; N, 2.02; S, 5.01.

After collection of the initial fraction, the flow reactor tubing waswashed with water using an HPLC pump. Initial measured backpressure forthe water wash was 200 psi. The reactor was then flushed with 15 mL ofxylene. Once the xylene had displaced water in the reactor coil, thebackpressure dropped to less than 5 psi. The xylene flush afforded amajor fraction of product; 3.58 g of a blue-green residue. UV-Vis (driedfilm) 284, 325, 768 nm; Elemental Analysis: C, 74.39; H, 9.99; N, 1.98;S, 4.77. Total yield from the 7.5 mmole scale reaction based on 1:1stoichiometry of PANI:DNNSA was 3.79 g (91.6%).

Current flow reactors, including micro-reactors, use microfluidic chipsor miniaturized columns and specialized equipment for control of theflow devices. The present system and method provides a device that canbe assembled from syringe pumps, commercially available HPLC tubing andan aluminum holder outfitted with a standard thermocouple temperaturecontrol device. By using syringe pumps to control the flow of reagents,the pressure in the reactor can be held well below the limits of theflow reactor tubing and low pressure fittings. Concentrations and flowrates of reagents can be chosen to provide an overall reactionconcentration similar to that used in batch processing. For example, forPANI-DNNSA, the overall reaction concentration after mixing can be 0.23M, which is very close to the value calculated for previously publishedbatch reactions.

While stoichiometry of the reagents used in the present disclosure wasapproximately one equivalent each of aniline, DNNSA and ammoniumpersulfate, other stoichiometry can be used. For PANI, monomerconcentration was limited by the solubility of aniline in water, whichat room temperature is slightly greater than 0.375 M. Thus, for theexemplary experiment using PANI, Pump A was charged with the 0.375 Maniline solution and delivered at 0.277 mL/min and the DNNSA solution,approximately 50% w/w in n-butylglycol or 1.04 M solution, was placed inpump B and delivered at 0.1 mL/min, and Pump C was charged with afreshly prepared 2M ammonium persulfate solution delivered at 0.05mL/min. Each reagent has a delivery rate of 0.1 mmole per minuteresulting in a total flow rate for the reaction mixture of 0.427 mL/min.Other total flow rates can be used commensurate with the systemparameters and polymer product.

It was noted that both the 1 mmole scale and the 7.5 mmole scalereaction provided two distinct fractions; an initial fraction wasobtained in the biphasic reaction mixture which was purified by theusual extraction route; and a larger scale reaction. The first fractionwas a minor component representing 5% of the total material.Unexpectedly, the major fraction adhered to the flow reactor tubing.While it did not completely inhibit flow through the reactor, it didincrease the back-pressure of the system. Thus, monitoring of thebackpressure was used to facilitate monitoring of the reaction process.Based on these results, it is possible to produce PANI-DNNSA product atrates of grams/day for a given flow reactor unit, for example, 10grams/day, or 20 grams/day, up to about 50 grams/day, of whichproduction amounts can be multiplied by the number of parallel flowreactors used. Thus, the present disclosure provides for a method ofproducing large quantities of compositionally consistent conductivepolymer salts such as PANI-DNNSA cost effectively and with relativelyhigh yield and high production rates.

In both trials, the reactor coil was washed with water to remove aqueousimpurities such as sulfuric acid and excess oxidant catalyst, while themajor product was obtained by flushing the flow reactor with xylene. Dueto the solubility of the PANI-DNNSA product, it is possible to obtainthe product in a minimum amount of xylene. The deposition of thePANI-DNNSA product is an advantageous result, allowing removal ofaqueous impurities and direct extraction of the polymer in xylene, forexample, without post-reactor workup and to provide a product that iscapable of being spun coated or precipitated.

FIG. 11 depicts a UV-Vis Spectra of PANI:DNNSA as a dried film, wherethe UV-Vis spectra 500 of an early first fraction shows similarity withthe UV-Vis spectra 550 of major late fraction as products. Expected UVabsorptions are seen for an aniline ring and the incorporation of thenaphthalene ring in the DNNSA salt. Elemental analysis was obtained andanalysis of the mole percent of N and S shows that these elements arepresent in equal molar amounts, suggesting a one to one ratio of thenitrogen component of PANI and the sulfonic acid of DNNSA or a polymericmaterial that is 1:1 PANI:DNNSA. Previously reported conductivePANI:DNNSA polymer was obtained in a 2:1 ratio. The present 1:1 materialis believed the result of a slight molar excess of DNNSA used in theprocess. Manipulation of the PANI:DNNSA ratio is possible with thepresent system and method and allows for varying the ratio in thefinished polymer product.

The initial trials with the present flow reactor device havedemonstrated the feasibility of preparation of conductive polymer saltsfrom monomers and acid. The system and methods disclosed provide forforming emulsions and introducing the emulsion along with catalyst to aflow reactor. By way of example only, PANI-DNNSA soluble polymer wasprepared by the present flow reactor process. For the PANI system, otherorganic acids for forming salts can be used. Other monomer/salt systemscan be used, such as thiophene/polystyrene sulfonate salt, or forin-situ doping during monomer polymerization of conductive polymers.

The description of preferred embodiments for this disclosure has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Obvious modifications or variations are possible in light ofthe above teachings. The examples are chosen and described in an effortto provide the best illustrations of the principles of the presentdisclosure and its practical application, and to thereby enable one ofordinary skill in the art to utilize the various examples and withvarious modifications as are suited to the particular use contemplated.

What is claimed is:
 1. A method comprising introducing an emulsion of amonomer and an acid into a flow reactor, the flow reactor comprising alength of tubing of inner diameter between about 1 to about 1000micrometers; polymerizing the monomer; and forming a salt of thepolymerized monomer with the acid within the length of tubing.
 2. Themethod of claim 1, further comprising introducing a catalyst to theemulsion.
 3. The method of claim 1, further comprising introducing acatalyst to the flow reactor.
 4. The method of claim 1, wherein theemulsion comprises an aqueous solution of the monomer and an organicsolvent solution of the acid.
 5. The method of claim 1 furthercomprising maintaining the salt of the polymerized monomer in the lengthof tubing.
 6. The method of claim 5, further comprising recovering thesalt of the polymerized monomer from the tubing.
 7. The method of claim6, wherein the recovering of the salt of the polymerized monomer fromthe tubing is with organic solvent.
 8. The method of claim 1, furthercomprising maintaining the polymerized acid salt in the length of tubingand removing unreacted monomer or the acid from the tubing with water.9. The method of claim 1, wherein the length of tubing is coiled. 10.The method of claim 1, wherein the tubing is a fluoropolymer.
 11. Themethod of claim 1, wherein the flow reactor comprises a plurality oftubing arranged in a parallel flow configuration.
 12. The method ofclaim 1, wherein the polymerizing is carried out in a diffusion-limitingcondition.
 13. The method of claim 1, wherein the monomer is an anilineor a thiophene.
 14. The method of claim 1, wherein the acid is anorganic acid selected from polystyrene sulfonate or dinonylnaphthalenesulfonic acid.
 15. A method comprising introducing an emulsion of ananiline and an organic sulfonic acid; introducing the emulsion into aflow reactor, the flow reactor comprising a length of tubing of innerdiameter between about one to about 1000 micrometers; introducing anoxidant to the emulsion or the flow reactor; and polymerizing theaniline in the inner diameter of the length of tubing and forming anacid salt thereof.
 16. A polymerization apparatus for reacting one ormore monomers producing one or more polymers, the polymerizationapparatus comprising: an amount of tubing of inner diameter betweenabout 1 to about 1000 micrometers, the tubing including at least oneinlet and at least one outlet, the amount of tubing having at least oneinlet port for receiving a reactant composition and at least one outletport; a temperature controller sized to receive at least a portion ofthe tubing; a mixing chamber, the mixing chamber having an outletfluidically coupled to the inlet of the tubing, and an inlet; at leastone pressure unit operatively coupled to one or both of the inlet portor the outlet port of the amount of tubing, the at least one pressureunit configured to monitor, during polymerization of the one or moremonomers, pressure in the amount of tubing or the difference in pressurebetween the inlet port and the outlet port of the amount of tubing; andat least one fluid flow control device fluidically coupled to the inletof the mixing chamber.
 17. The polymerization apparatus of claim 16;wherein the tubing is wound around the temperature controller.
 18. Thepolymerization apparatus of claim 16; wherein the at least one fluidcontrol device comprises a monomer fluid flow control device and an acidfluid flow control device.
 19. The polymerization apparatus of claim 16,further comprising a second mixing chamber fluidically coupled to theoutlet of the mixing chamber and the inlet of the tubing.
 20. Thepolymerization apparatus of claim 16, further comprising a catalystfluid flow control device fluidically coupled to the second mixingchamber or to the tubing.